Add and Remove some functions in klist.h etc

[Haerxile]

It's part of the final class project.

What's changed?

1. Remove func set_both_kvec_after_vc for it do the same as set_after_vc
2. Remove two useless parameters in func set_after_vc
3. Remove func K_Vectors::mpi_k_after_vc for it do the same as mpi_k
4. Remove func set_kup_and_kdw_after_vc for it's useless now
5. Add a function Linely_add_k_between to make the func read_kpoints more readable
6. Add a func pool_collection_aux to deal with the repeat of pool_collection
7. Move ibz2bz to private
8. Add notes in doxygen and modify the code indentation format
9. Fixed a missspelling of symm.equal(a.e32, b.e32) in auto matequal

Thanks to kirk0830's suggestions, more changes were made as follows:

10. Rename some sick-named variables
11. Add a param of ofstream& ofs to take place of GlobalV::ofs_running in func set
12. Make some of the if-elses of nspin clearer
13. Fixed a small misswriting of max_kpoints

[mohanchen]

nice job, I will discuss with you about the PR proposed by another group.